Saturday, July 15, 2006

Effect of installing 100 CFLs

Just before installing our solar thermal system, I replaced 100+ normal lightbulbs with CFLs (more efficient lights). And no, the main house does not use 100 lightbulbs...we have 7 houses on the premises: 1 main and 6 smaller. The main house uses about 50 with ~10 per small house.

Each CFL uses ~50W less than the original bulb, so that adds up to 5 kW less consumption capacity. Not all lights are on at the same time (despite the best efforts of my 20+ nieces and nephews), so even if a maximum of 30 are used at once, that is a reduction of 1.5kW (50W x 30 bulbs) for each hour they are on. If those 30 bulbs are on 3 hours a day x 365 days/yr (~1100 hours/yr), we will save 1,650 kWh of energy use in a year.

At our ridiculous low $0.065/kWh rate, that adds up to a whopping $107 :-(

Looked at another way, a 1kW solar pv system costing ~$10k (minus incentives) would produce 1,650 kWh in a year (365 x 4.5 hrs of sun). I feel much better about my $200-$250 investment in CFLs now. :-)

[Our seven houses combined used 100,000+kWh last year. Sigh! More conservation to do.]


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